Year 5 - Maths
Estimate acute and obtuse angles using the standard unit of degrees
Angles: compare, name, estimate and measure angles
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
In this unit pupils will compare the size of angles where there is a clear visual difference and use the terms acute, obtuse and reflex when describing the size of angles or amount of rotation with relation to right angles using a unit called degrees.
Lesson Summary
You will learn to estimate acute and obtuse angles using the standard unit of degrees.
Key Notes
- You can estimate angles by comparing to a right angle of 90 degrees.
- Half a right angle is 45 degrees.
- One and a half right angles are 135 degrees.
Vocabulary To Learn
- Estimate: To estimate is to find a value that is close enough to the right answer, usually with some thought or calculation involved.
- Degree: A degree is a unit of measure for angles.
Common Mistakes To Avoid
- Pupils significantly over or under-estimate the size of angles, particularly when the initial line of the angle is not vertical or horizontal.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
You can estimate angles by comparing to a right angle of 90 degrees. Half a right angle is 45 degrees.
2. Use this key word in a maths sentence and explain it clearly. 'Estimate'
To estimate is to find a value that is close enough to the right answer, usually with some thought or calculation involved. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Pupils significantly over or under-estimate the size of angles, particularly when the initial line of the angle is not vertical or horizontal. Correction: Encourage pupils to rotate the angle so that one of the lines is vertical or horizontal, or if possible, look at the angle from a different point of view which may help to view a line of the angle from a vertical or horizontal position.
More Lessons In This Unit
- Angles in quadrilaterals Study Guide
- Angles in triangles Study Guide
- Describe rotations using the standard unit of degrees when compared to a right angle Study Guide
- Describe static angles using the standard unit of degrees when compared to a right angle Study Guide
- Draw angles accurately using a protractor Study Guide
- Know that the angles at a point sum to 360 degrees and use this to solve problems Study Guide
- Know that the angles in a full turn sum to 360 degrees and use this to solve problems Study Guide
- Know that the angles on a straight line sum to 180 degrees and use this to solve problems Study Guide
- Measure the size of angles accurately using a protractor Study Guide
- Reasoning about angles in polygons Study Guide
- Review understanding and identification of right angles Study Guide
- Review understanding of angles as a measure of turn Study Guide
- Use the terms acute, obtuse and reflex when comparing angles to a right angle Study Guide
- Use the unit of degrees as a standard unit to measure angles Study Guide
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